Back when I did hourly reporting I used http://timingapp.com/. It tracks what applications and windows are open and then you connect those to tasks/projects/etc later, which was a must for me since I always forgot both to do time reporting and what I had been working on.
(I am not associated with Timing, just a happy user)
I tried a few time tracking apps, and none come close to Timing. It's easy to use, gets regular updates, it's easy to setup projects and define rules (such that you don't have to track by hand). Has a handy integration with calendar, you can directly book meetings.
